How does caching help a name service’s availability?

What will be an ideal response?

Clients cache both object attributes and the addresses of servers that store directories. This helps the service’s availability because the client may still access cached attributes even if the server that stores them crashes (although the attributes may have become stale). And if, for example, the server that stores the director / emerald has crashed, a client can still look up the object /emerald/green/stone if it has cached the location of the directory /emerald/green.